Direct positive-type multi-layer light-sensitive material

ABSTRACT

A direct positive type photographic material having a high information packing capacity, which is in particular, a multilayer direct positive-type light-sensitive material comprising, on a suitable support member, at least two emulsion layers with the emulsion layers being selected from (A) a chemically fogged direct positive-type emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on the silver halide grains having free electron trapping nuclei in the grains, (B) a chemically fogged direct positive-type emulsion in which at least an electron acceptor is adsorbed on the silver halide grains substantially free from positive hole trapping nuclei in the grains, and (C) a chemically fogged direct positive-type emulsion in which at least a halogen acceptor is adsorbed on the silver halide grains having free electron trapping nuclei in the grains but substantially free from positive hole trapping nuclei in the grains, said emulsion layers being composed of the same type emulsion layers or different type emulsion layers having an intermediate layer therebetween.

United States Patent Shiba et a].

DIRECT POSITIVE-TYPE MULTI-LAYER LIGHT-SENSITIVE MATERIAL Filed:

Assignee:

Inventors: Keisuke Shiba; Hiroyuki Amano;

Hirozo Ueda; Akira Sato, all of Kanagawa, Japan Fuji Photo Film Company, Ltd., I

Kanagawa, Japan Apr. 20, 1972 Appl. No.: 246,074

[30] Foreign Application Priority Data Apr. 20, l97l Japan 46-24967 52 11.5. CI. 96/101, 96/64 [51] int. Cl. G03c 1/36 [58.] Field of Search 96/101, 64, 64 DP [56] References Cited 7 UNITED STATES PATENTS 3,647,463 3/1972 Taber 96/64 3,445,235 5/1969 Burt 96/l0l 3,50l,306 3/1970 lllingsworth 96/101 3,632,340 1/1972 lllingsworth 6/10] 3,531,290 Litzerman n. 96/101 Primary Examiner-David Klein Assistant Examiner.lohn L. Goodrow Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak 5 7 ABSTRACT A direct positive type photographic material having a high information packing capacity, which is in particular, a multi-layer direct positive-type light-sensitive material comprising, on a suitable support member, at least two emulsion layers with the emulsion layers being selected from (A) a chemically fogged direct positive-type emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on the silver halide grains having free electron trapping nuclei in the grains, (B) a chemically fogged direct positive-type emulsion in which at least an electron acceptor is adsorbedon the silver halide grains substantially free from positive hole trapping nuclei in the grains, and (C) a chemically fogged direct positivetype emulsion in which at least a halogen acceptor is adsorbed on the silver halide' grains having free electron trapping nuclei in the grains but substantially free from positive hole trapping nuclei in the grains, said emulsion layers being composed of.the same type emulsion layers or different type emulsion layers having an intermediate layer therebetween.

32 Claims, 27 Drawing Figures DIRECT POSITIVE-TYPE MULTI-LAYER LIGHT-SENSITIVE MATERIAL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a direct positive-type multilayer light-sensitive material having at least two layers of silver halide emulsions, in a particular combination, in which an electron acceptor and/or a halogen acceptor is absorbed or chemically fogged silver halide grains with the layers being selectively and directly-reversal sensitized to a particular wavelength range. More particularly, it is concerned with a direct positive-type multi-layer color light-sensitive material.

2. Description of the Prior Art With the advent of the information age, information recording materials having a high information packing capacity have been desired, by which recording can be carried out rapidly and simply. To this end, silver halide photographic materials appear to be suitable. A silver halide photographic material ordinarily results in a negative image by processings involving only one development. To obtain a positive image, therefore, such a negative image obtained by a series of developing processings has to be subjected to exposure and then to a series of developing processings again. Another method for obtaining a positive image from an object is a reversal developing system which comprises ordinarily a first development, a water washing, a bleaching, a water washing, a cleaning bath, a water washing, an exposure or fogging bath, a second development, a fixing and a water washing. Color reversal development processing comprises a first black-and-white development, a stopping, a hardening bath, a water washing, an exposure or fogging bath, a water washing, a color developing bath, a water washing, a bleaching, a water washing, a

fixing, a water washing and a stabilizing bath, which are generally time consuming and very complicated. In general, it is more advantageous to recordan object as a positive image.

There are a number of methods to increase the recording information capacity of a silver halide photographic material. If the resolving power, sharpness and grain property of an image are improved then the information capacity per unit area can be increased. It is knwon to raise the information density by increasing the thickness when the light-sensitive material is multilayer. It is also known to raise the recording density by varying the wavelength range of the spectral sensitization of each silver halide photographic emulsion used. For example, electron rays, x-rays, ultraviolet rays, blue light, green light, yellow light, red light and near infrared rays can be classified by wavelengths and recorded and the recording density can be raised by vary ing the color hue (the spectral adsorption characteristic) of the recorded image, for example, by the use of a yellow image, a magenta image, a red image, a cyan image and a blue image.

Furthermore, direct positive-type silver halide photographic emulsions which have been previously chemically fogged have a much higher developing speed than a photographic emulsion having a latent image obtained by the ordinary negative type exposure. Therefore, this is very advantageous to a rapid process.

It is further advantageous from a commercial standpoint that the direct positive-type silver halide photographic material designed for a specific use is able to give a positive image directly from an object by subjecting such a material to the usual color paper; processing,

litho-type development, color positive-type development for movie use, x-ray rapid development or color negative processing. To obtain such a multi-layer, direct positive type silverhalide photographic material, there are more difficulties on the composition of at least two emulsion layers as compared with the commonly used multi-layer negative light-sensitive material. The instant invention solves this technically difficult problem.

A first object of the invention is to obtain a direct positive-type light-sensitive material having a high information recording capacity, in particulana multilayer direct positive type light-sensitive material comprising at least two layers.

A second object of the invention is to obtain a multilayer, direct positive-type light-sensitive material by which a positive image from a positive object or a negative image from a negative object can be obtained economically and in a short period of time through the use of only the ordinary series of negative developing processings.

A third object of the invention is to obtain a multilayer, direct positive-type photographic material whose information recording capacity is raised by varying the sensitized wavelength region of each silver halide photographic emulsion layer.

A fourth object of the invention is to obtain a direct positive-type color photographic material whose information recording capacity is raised in place of the color hue (the spectral adsorption characteristic) of a directly obtained positive image.

A fifth object of the invention is to obtain a direct positive-type silver halide photographic material whose exposure latitude is enlarged by use of a composition of at least two layers and whose information recording capacity is raised with a change in the quantity of exposure. Further objects of the invention will be apparent from the following detailed description.

SUMMARY OF THE INVENTION The above described objects of the invention can be accomplished by a direct positive-type multi-layer light-sensitive material comprising, on a suitable support, at least two emulsion layers selected from the group consisting of (A) a chemically foggeddirect positive-type emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on silver halide grains having free electron trapping nuclei inside the grains, (B) a chemicallyfogged direct positive-type emulsion in which at least a halogen acceptor is adsorbed on silver halide grains which are substantially free from positive hole trapping nuclei inside the grains, and (C) a chemically fogged direct positive-type emulsion in which at least an electron acceptor is adsorbed on silver halide grains having free electron trapping nuclei inside the grains but substantially free from positive hole trapping nuclei inside the grains, said emulsion layers being composed of the same type of emulsion layer or a different type of emulsion layer having an intermediate layer therebetween.

The multi-layer, direct positive-type light-sensitive material according to the invention is capable of giving a positive image rapidly, simply and directly utilizing the commonly used negative developing process for black-and-white or color photography.

FIG. 1 to FIG. 3 and FIG. 19 to FIG. 25 show, for comparison, the characteristic curves obtained from various light-sensitive materials according to the invention.

FIG. 4 to FIG. 7 show schematically the layer structure of direct positive-type silver halide photographic emulsions according to the invention.

FIG. 8 to FIG. 18 show spectrograms of films on which complete emulsions of the invention are coated.

DETAILED DESCRIPTION OF THE INVENTION The multi-layer, direct positive-type light-sensitive material comprising at least two layers provided by the present invention is applicable to miscellaneous uses such as: reproduction of an original consisting of points, lines or patterns of at least two colors; recording or reproduction of an image-consisting of at least two colors on a cathode-ray tube; formation of a contour image from a predetermined object, enlargement or duplication of a color photograph from a color transparent positive or negative photograph using one conventional color development prosess; and duplication of a radiograph.

Ordinarily the following disadvantages occur when the commonly used direct positive emulsions are stacked corresponding to the arrangement used in a multi-emulsion layer using negative-type emulsions. The direct positive emulsion having a high sensitivity, a hard gradation and a good clearance loses these properties when stacked. A confusing of the spectral sensitivity distribution of the emulsion layers occurs and, in the case of a color photographic material, a surprising mixing ofcolors results. The invention provides a-technique for coping with such disadvantages, which will be apparent from the detailed description and examples embodied.

-l. The type of each direct positive emulsion (which will hereinafter be defined) is confined Preferably a multi-emulsion layer is composed of same type emulsions only.

2. An intermediate layer suitable for the invention is provided. Tothis intermediate layer are added a fine grain silver halide emulsion in an amount. sufficient to prevent diffusion of an electron acceptor or a halogen acceptor, adsorbents, charged hydrophilic high molecular weight materials and surface active agents (including couplers). With a color photographic materials, in particular, a fine grain light-sensitive silver halide emulsion, at surface active agent and a color coupler are added to provide an auto-masking mechanism, thus preventing color mixing. 7

3. A simultaneous multi-layer coating method is used. Between the emulsions which are coated simultaneously, there is relatively little undesirable interaction due to the mutual diffusion'of an electron acceptor or a halogen acceptor.

4. Other methods will be apparent from the following illustration.

The types of the direct positive-type silver halide emulsion used in the invention will now be illustrated in detail. These specific illustrations are not to be interpreted as limiting the invention thereby.

Emulsion A A chemically fogged silver halide photographic emulsion having free electron trapping nuclei inside the silver halide grains:

This direct positive emulsion has nuclei capable of trapping free electrons inside the silver halide grains and the surface of the grains is chemically fogged. The

free electrons generated in the fine crystals of silver halide by direct radiation of photons. On the other hand, the positive holes whose recombination with free electrons is interrupted attack the fog nuclei previously provided to the crystal surface, thus oxidizing the fog nuclei and inactivating the developing activity. Conse-' quently, a positive image is directly formed by development depending on the quantity of the radiation received (that is, imagewise). Regarding Emulsion A, a number of techniques can be used for improving the intensification, i.e. raising the reversal sensitivity or for lowering the minimum density, i.e. improving the clearance.

First, electron trapping nuclei can be provided inside of the silver halide so as to prevent recombining of the positive holes and free electrons generated in the silver halide by radiation with photons.

A second technique is to provide fog nuclei which are chemically attacked by the positive holes-thus losing readilythe developing activity of the surface layer of the silver halide.

A third technique is to adsorb an electron acceptor capable of trapping any free electrons generated on the silver halide. The adsorbed electron acceptor will not trap positive holes.

Emulsion A is an emulsion which gives a positive image directly. This emulsion can be spectrally sensitized by adsorbing a halogen acceptor or sensitizing dye thereon. The halogen acceptor produces free electrons on the silver halide due to light excitation on radiation and, at the same time, produces positive holes on the surface of the silver halide. If the free electrons are trapped by free electron trapping nuclei inside the silver halide or trapped by the adsorbed electron acceptor and prevented from recombining with positive holes, the positive holes generated on the surface of silver halide attack the fog nuclei more readily and effectively making them development inactive.

A fourthtechnique is to maintain the silver halide grains at a suitable grain size so that the positive holes generated on the silver halide by radiation with photons are easily removed to the surface due to the effect of the surface electric field of the silver'halide grain and thereby attack fog nuclei. The emulsion to which this technique can be applied has a high sensitivity and clearance. However, this unfortunately results in a gradation being hard and unsuitable for reproduction of details.

For Emulsion A, a silver chloride, silver bromide, silver iodide or a mixed silver halide thereof photographic emulsion is used. It is necessary to choose the halogen composition so that a chemical sensitizer or a group VIII metal salt used for providing free electron trapping nuclei may readily be incorporated in the silver halide. A characteristic of Emulsion A is that it is capable per se of giving a positive image directly and not only sensitization of the intrinsic absorption region but also spectral sensitization are made possible by the addition of a halogen acceptor.

The clearance is improved and the formation of a negative image is prevented by adding an electron acceptor. Furthermore, the addition of bromide ion or iodide ion results in increasing the optical density on a nonexposed area, raising of the sensitivity and improvement of the clearance.

Emulsion B A chemically fogged silver halide emulsion substantially free from positive hole trapping nuclei inside the silver halide grains:

If some free electron trapping nuclei are provided to the silver halide, the free electron trapping function tends to accelerate the recombining of the positive holes. Emulsion B is a direct positive emulsion whose silver halide surface is chemically fogged and which is free from positive hole trapping nuclei and free electron trapping nuclei inside the silver halide. This is a si1- ver halide emulsion consisting of a regular crystal which is as free from crystal defects as is possible and which is, preferably, a pure silver bromide, silver bromoiodide or silver chlorobromide free from twin surfaces. This emulsion per se gives no positive image 'directly. When an electron acceptor or a desensitizing dye is absorbed on Emulsion B, however, a high sensitivity direct positive image is obtained, which is spectrally sensitized and, even in the intrinsic absorption region, a high sensitivity positive image is obtained. When an electron acceptor and a halogen acceptor are adsorbed on the silver halide grains of Emulsion B, the clearance deteriorates markedly and the sensitivity is reduced. A halogen acceptor is quite suitable as a sensitizer for Emulsion A type but, for Emulsion B type, it has the disadvantages that the clearance deteriorates and the sensitization is reduced. This is noticed for the production of a direct positive photographic material consisting of at least two layers.

Emulsion C A chemically fogged silver halide emulsion such as a silver chloride, a silver bromide, silver chlorobromide, a silver bromoiodide or a silver chlorobromoiodide emulsion, having free electron trapping nuclei inside the grains but which is substantially free from positive hole trapping nuclei inside the grains:

This is an emulsion consisting of such grains that free electron trapping nuclei are provided in the central nuclei of silver halide, the outer shell of which is covered by silver halide and the surface is chemically fogged.

Electrons generated in the silver halide on radiation are trapped by the central nuclei whereby the so-called internal latent image nuclei is formed. Since there are no free electron trapping nuclei in the outer shell, positive holes effectively attack fog nuclei very near the surface of silver halide grains and the probabilityof recombining with free electrons is low. Accordingly, Emulsion C has the features that it, per se, gives a direct positive image which is hard and has a high sensitivity and that it does not give a negative image even through exposure to more radiation, that is, the clearance is good.

At the present time, processes for the production of an emulsion having internal nuclei of this kind are well known (e.g., see Japanese Patent Publication 29405/ 1968). An example of the application thereof to a direct positive type emulsion is described in British Patent Application No. 16507/66. The use ofa halogen acceptor is effective for Emulsion C as in the case of Emulsion A, but the effect of the electron acceptor is small.

A halogen acceptor and anele'ctron acceptor and, above-all, the halogen acceptor to be added to the emulsion used in the invention has such a weak adsorptive ability to silver halide grain that a larger amount has to be added than is used in the conventional negative emulsion. In the case of a multi-layer construction, the interlayer diffusion of an electron acceptor tends to become great and, in addition, the undesirable action of interlayer diffusion of a halogen acceptor becomes more marked in comparison with a negative emulsion. This effect is strengthened if a color coupler is present. In particular, a halogen acceptor has the disadvantage that, particularly if Emulsion B is only slightly contaminated by it, the direct reversal sensitivity is lost.

Technical aspects of the production of emulsions of various types used in the invention will now be illustrated in detail. v

The fog nuclei in the invention are provided by previously chemically fogging a silver halide emulsion, that is, by adding an inorganic reducing compound, such as stannous chloride or boron hydride, or an organic reducing compound, such as a hydrazine derivative, formalin, thiourea dioxide, a polyamino compound, aminoborane or methyldichlorosilane. The fogged nuclei of the invention, whose keeping property is improved, tend to bedecomposed by positive holes. That is to say, the fogged nuclei are obtained using a fogging method which advantageously gives rise to high sensitization and good storage properties of a direct positive emulsion. For example, the combined. use of melted. reducing agent with an ion more noble than silver ion or with a halide ion is known (e.g., see U.S. Pat. Nos. 2,497,875; 2,588,982; 3,023,102; and 3,367,778;-Brit'- ish Pat. Nos. 707,704; 723,019; 821,251; and 1,097,999; French Pat. Nos. 1,513,840; 1,518,095; 739,755; 1,498,213; 1,518,094; 1,520,822; and

chemically ripened emulsion, the outer shell of the silver halide having light-sensitive nuclei obtained by chemical ripening is further coated with pure silver halide to convert them into internal nuclei, and a Group VIII metal salt or Group Ib salt is added during the step of forming a precipitate of the silver halide (e.g., see U.S. Pat. Nos. 2,401,051; 2,717,833; 2,976,149 and 3,023,102; British Pat. Nos. 707,704; 1,097,999 and 690,997; French Pat. Nos. 1,520,822; 1,520,824; 1,520,817 and 1,523,626; Japanese Pat. Publication Nos. 4125/1968 and 29405/1968, and Belgian Pat. Nos. 713,272; 721,567 and 681,768).

It is necessary, in order to avoid providing positive hole trapping nuclei to the inside of the silver halide, to use cubic system or tetragonal system grains both having the surface free of twin surfaces and having a regular crystal habit substantially free of crystal defects so as not to provide free electron trapping nuclei to raise the probability of recombining with free electrons to at least the sub-surface layer near the surface of the grain (e.g., see British Application Nos. 11291/67, 11292/67 and 16507/66).

For the emulsion types used in the invention, gelatins, in particular, inert gelatins, are advantageously used as a protective colloid. Inplace of natural gelatins, photographically inert gelatin derivatives and watersoluble synthetic polymers, for example, polyvinyl acrylate, polyvinyl alcohol, polyvinylpyrrolidone and polyvinyl alginate may be used.

The electron acceptor,'desensitizer or desensitizing dye used inthe invention is a material which is generated in the silver halide grain by radiationwith photons, which is capable of trapping free electrons and which is adsorptive on silver halide. It is further defined as a material having a minimum energy level of vacant electron which is lower than the electron energy level of the conduction band ofthe silver halide grain. Preferably, it is a desensitizing dye having a maximum energy level of occupied electrons, which is lower than the valency band of the silver halide grain. Measurement of the values of these energy levels is complicated, but is possible. For example, determination of these energy levels for a very simple symmetric cyanine dye is described in Photographic Science and Engineering by Tani. and Kikuchi, Vol. 11 (3), page 129 (1967} and determination for a typical merocyanine dye is described in Preprim (No. B-l2) of lCPS-1970 (Moscow) by Shiba and Kubodera. It is known that these electron energy levels correspond primarily to the anodic polarographic halfwave potential (Eox) and cathodic polarographic halfwave potential (Ered). Many of the foregoing compounds are disclosed in, for example, U.S. Pat. Nos. 3,023,102; 3,314,796; 2,901,351 and 3,367,779; British Pat. Nos. 723,019; 698,575; 698,576; 834,839; 667,206; 748,681; 796,873; 875,887; 905,237; 907,367 and 940,152; French Pat. Nos. 1,520,824; 1,518,094; 1,518,095; 1,520,819; 1,520,823; 1,520,821 and 1,523,626; Belgian Pat. Nos. 722,457 and 722,594, Japanese Pat. Publication Nos. 13167/1968 and 14500/1968. The electron acceptor used in the invention is a desensitizing dye whose cathodic polarographic half-wave potential (Ered) is more positive than l.0'volt.

The halogen acceptor or sensitizing dye used in the invention is a material capable of producing free electrons in the-silver halide grain while absorbing light itself while in the state of being adsorbed on silver halide photographic emulsion grains and, more importantly, is a material capable of producing positive holes having an energy sufficient to oxidize fog nuclei on the surfaces of the silver halide grains. The halogen acceptor cannot be defined absolutely in terms of its electron energy level, that is, by comparison of the energy levels.

of the valency band and the conducting band of silver halide, because, in many cases, the mechanism of energy transfer is attributed to the specific specific spectral sensitization process. Many known sensitizing dyes can act asa halogen acceptor in the state of M-band type adsorption either by themselves or with a suitable supersensitizer. That is to say, the halogen acceptor may be defined as a sensitizing dye of the M-band type.

The halogen acceptor used in the invention is preferably a sensitizing dye whose cathodic polarographic half-wave potential is more negative than -0.7 volt and difference between the cathodic polarographic halfwave potential and the anodic polarographic half-wave potential is greater than 1.5 volts. Such a compound is, for example, selected from dyes described in U.S. Pat. Nos. 2,497,876 and 3,364,026, French Pat. Nos. 1,520,822 and 2,012,545, British Pat. No. 655,009 and German Pat. No. 1,190,331.

The value of the cathodic .polarographic half-wave potential (Ered) is the value in volts of the potential at which the compound accepts an electron at the cathode. As used in this invention, it is determined using tetra-n-propylammonium perchlorate as a support electrolyte, a dropping mercury electrode at 25C in a solution of acetonitrile with a saturated calomel electrode as a reference electrode, and further it is measured in a solution of acetonitrile at a concentration of from 1 X 10" mol to l X 10' mol.

The value of the anodic polarographic half-wave potential (Box) is the value in volts of the potential at which an electron is withdrawn from the compound at the anode. As in the case of Ered, it is measured using a rotary platinum electrode as the. anode and sodium perchlorate as a support electrolyte according to the methoddescribed in German Pat. No. 2,010,762.

The amount added of the electron acceptor or the halogen acceptor used'in-the invention may be varied depending on the amount of silver halide in an emulsion, the size of the surface area of the silver halide and the object of the elements use. The halogen acceptor is used in a greater amount than is used than in the conventional negative type emulsion, because there is no desensitizing action due to a sensitizing dye occurring in the negative emulsion. The above described amount to be added may preferably-range from about 1 X 10 plication 8231/1970, Japanese Pat. Publication Nos.

23389/1969; 27555/1969, and 22948/1969, U.S. Pat.

Nos. 3,485,63; 3,342,605 and 2,912,343 and German Offenlegungsschrift No. 1,947,935.

The intermediate layer used in the invention must have different characteristics from those commonly used in a negative-type multi-layer light-sensitive material. That'is to say, on the characteristics of the intermediate layer, efforts have to be made to prevent diffusion of the electron acceptor or halogen acceptor. Fine grain silver halide or silica, for example, a grain size less than about 0.2 microns, is contained therein in an amount sufficient to prevent diffusion for example, less than g/ g of dry gelatin. in the case of a negative emulsion type multi-layer light-sensitive material, provision of such an intermediate layer desensitizes an adjacent layer. If the intermediate layer is provided in a direct positive type multi-layer light-sensitive material, on the other hand, the sensitivity of silver halide grain in the intermediate layer is lowered due to the adsorption of the electron acceptor and an adjacent layer is not desensitized in spite of the fact that a larger amount is used than in the case of the negative type. A high molecular weight anionic organic compound or anionic surface active agent such as sodium naphthalenesulfonate described in Japanese Pat. Publication 23309/ 1965 and 23310/1965 is added in an amount sufficient to prevent diffusion of the halogen acceptor or electron acceptor by static reaction or solubilization, for example, from about 5 to 50 g per 100 g of gelatin. Preferably a fine grain light-sensitive silver halide having a suitable negative sensitivity and suitable for prevention of the diffusion thereof may be mixed with a suitable amount of a color coupler to thus give an automatic masking mechanism in a direct positive-type multilayer light-sensitive material. The combined use of a cationic hydrophilic polymer can prevent diffusion of the electron acceptor or halogen acceptor having acidic groups. Further this may previously be dyed so that it will function additionall as a li ht filter la er, an 10 irradiation prevention layer aiid an a iitihalation layer. i (75 g of inert gelatin a dlssolvefj m 300 of Suitable cationic hydrophilic Polymers which can be water) to'obtam a sllver hahqe emul.slon comammg used in the invention are, for example, polymers of 2- regfllar, tetragonal Ystem grams havmg an average methyl-l-vinylimidazole, the quaternized derivatives gram of thereof, polymers of vinylpyridine, and polymers of Emulsion C v N,N-dlalkylamlnoethyl methacrylate and quaternlzed derivatives thereof. From 2 to g of these polymers This is P p y the Similar P u to those of is used per 100 g of dry gelatin. Anionic hydrophilic Emulsion A excel)t for the following Points: polymers which are suitable for use in this invention T0 the first Solution P p as in Emulsion A Were are, for example,- polymers of a r li id d meth- 20 gradually added one half of the second solution preacrylic acid and copolymers of maleic anhydride and pared as in Emulsion A and A BI Solution styrene-sulfonic acid, and they can be used at a level of g of sodium chloride and l 1.5 g of potassium bromide about 0.5 to 50 g per 100 g of dry gelatin, were dissolved in 75 ml of water, in which 50 mg of iridium potassium hexachloride was additionally dissolved) with agitation for a period of 10 minutes, followed by ripening for 5 minutes. Then .the remaining EXPERIMENTS half of the second solution and Ill 2nd solution l 1.5 Emulslen A g of sodium chloride and 11.5 g of sodium bromide To a fi t solution 0 g f inert gelatin and 5 1 f were dissolved in 75 ml of water) were gradually added a 1 N solution f Sodium chloride in 500 1 f water for 20 minutes. Thereafter,.a similar procedure to that were warmed to 60C and dissolved) were constantly deseribeq for Emuision A ep thus Obtaining 3 added a second solution (100 g of silver nitrate in 500 Silver hahde emulslon eonslstmg of regular tetregonal ml of water was warmed to 60C and dissolved) and a System grains having the Surface and an average third solution 23 g of sodium chloride and 2,3 g of pograin Size of 018 microntassium bromide were dissolved in 150 ml of water, to yp embodiments e making t 3 f which 50 mg of iridium (IV) potassium hexachloride C are shown above- Delleate p y "Pe eondl' was further added, and warmed to 60C) with agitation time. for a p the Shape of a vessel, stlrring blade, for a period of ninut es Thereafter of a stirring speed and feed positions Of th second SOiLltiOll N solution of potassium iodide was added, the mixture and the third Solution, the degree Of Water Washing and cooled and washed with water, followed by melting, ad- 40 other delicate gg conditions affect largely the P ejusting the pAg to 4.0, adding hydrazine and potassium tegraphie eharaeteristieschloroaurate, adjusting the pH to 10, ripening for 10 To each of the silver halide emulsions were added a minutes and neutralizing to a pH of 6.5 with citric acid. p fi electron acceptor or halogen acceptor The temperature was lowered, followed by washing h n in Table and a r n Such asa formalin, with water, a mixed solution of sodium chloride and poichl0r0-5-hydroxy riazine, or chromium alum, and a tassium bromide is added, the pAg is adjusted to 7.0, coating aid, such as saponin or nonyl-benzene sulfonate and further a fourth solution (75 g of inert gelatin was and coated onto a transparent cellulose triacetate film dissolved in 300 ml of water) was added to give a silver to thus obtain a direct positive sensitive material. It was halide emulsion. The so obtained silver halide emulsubjected to light wedge exposure usingatungsten light sion, having an average grain size of 0.15 micron, conof 2854K as a light source, and developed at 20C for sisted of regular tetragonal system grains, substantially 2 minutes using a developer of the following composi all of the grains having the surface (100). tion. The density of the thus obtained strip was measured using of an S-type densitometer made by the Fuji Emulslon B Photo Film Co. The results obtained are shown in To a first solution (8 g of inert gelatin and 5 ml of a FIGS. 1, 2 and 3 in which the characteristic curves are l N solution of potassium bromide in 500 ml of water given. were warmed at C and dissolved) were addeda sec- The structural formulas of the electron acceptor and 0nd solution g of silver nitrate in 500 ml of water the halogen acceptor used are shown in the following: was warmed at 60C and dissolved) and a third solution 60 Halogen Acceptors:

(a) l =CH-Ch=l l A l O I C H C 1-1 5 10 (70 g of potassium bromide in ml of water was warmed at 60C and dissolved) gradually with agitation for a period of 50 minutes, followed by physical ripening for an additional 5 minutes. adding l5 ml ofa 0.2! N solution of potassium iodide and then adjusting the pAg to 6.0 using a silver nitrate solution. Hydrazine and potassium chloroaurate were added, the pH was adjusted to 10 with a solution of caustic soda followed by ripening. The mixture was neutralized with citric acid, washed with water, melted and mixed with a fourth so- Electron Acceptors:

(n) -cH=cH-cr1 N/\/ r T i 5 CH 5 /N V I J CH=CH I N N t I CH5 0 S CH Dewiogerlcmnfiifion e formed with an increase of exposure is remarkably supn gtg (about C) 9 2 pressed and the clearance is improved. On the other Anhydrous Sodium Sulfite 45 g hand, Emulsion B does not give a direct positive image g gg fiq %g gg Monoh dmte g by itself but the reversal sensitivity can be raised markpomgsium Bromide y 2 g edly by the addition of anelectron acceptor. ln Emul- Water to 1000 ml This is diluted with water in a proportion of l l.

t It will be apparent from the results obtained in Experiments No. i, No. 2and No. 3, and shown in FIG. 1 that sion C, the effect of the electron acceptor is less than in Emulsion A. The halogen acceptor raises markedly the reversal sensitivity in Emulsion'A and, at-the same time, tends to form a negative image with an increase of exposure. This can be suppressed by the combined use with an electron acceptor. It is also observed in Emulsion C that the reversal sensitivity is markedly raised. In Emulsion B, however, the coexistence of the halogen acceptor (a) and (b) in Experiment No. 2) weakens the reversal property, lowers the reversal sensitivity and deteriorates the clearance. Other additives Table I No. Emulsion Halogen Acceptor Electron Acceptor Characteristic 100 g (mol cone) ml (moi conc) ml Curve 1 Type A FIG. I Curve 1 (a) (2 X 10") 8 2 (m)(8 l)4 3 (a) (2 X W) 8 (m) (8 X 10") 4 4 (a)(2 l0)8 (0)(l.6Xl0 )4 5 2 Type B i FIG. 2 Curve-l (2 X IO') 2 2 (n) (4 X IO") 4 3 (o) (1.6Xl0) 4 4 (a) (2 X l0) 2 (n) (4 X 4 5 (b) (2 X 10') 2 (n)( do. )4 (v 3 Type C FIG. 3 Curve 1 (b)(2 10*)4 2 .(m)(8 l0")4 3 (m)(8 l0)4 4 (Ta) (2 x 10-" 4 to be added to the emulsion, for instance, color couplers, coating aids, stabilizers, development accelerators and hardeners exhibit different photographic effects according to the kind of emulsions, Emulsions A, B and C.

In the direct positive-type multi-layer light-sensitive material according to the invention, at least two coating emulsions of the invention are applied to a suitable support base using a simultaneous multi-layer coating method as disclosed in, for example, US. Pat. No. 2,761,791. The system of coating the emulsion layers individually is most disadvantageous, because simultaneous multi-layer coating can substantially reduce deleterious interactions between the emulsion layers. However, when an emulsion or gelatin solution is coated thereonto, the interaction between the previously coatedlayers increases. Such disadvantageous interaction between emulsion layers can be avoided by provision of a specific intermediate layer as illustrated before.

The disadvantageous interaction between emulsion layers consisting of at least two layers due to mutual diffusion of the electron acceptors and the halogen acceptors used in the emulsions can be solved by the using of those materials which have a strong adsorptive capacity on the silver halide grains and by provision of a specific intermediate layer. In the case of high interaction emulsion types, for example, Emulsions A and B or Emulsions C and B, the simultaneous multi-layer coating technique is very effective.

The above described improved method which is necessary for provision of a high quality direct positivetype multi-layer light-sensitive material is for the first time clarified by the instant invention.

The particularly preferred electron acceptors used in the invention are compounds represented by the following General Formula (I) or (II).

General Formula (l) wherein Z is an atomic group necessary for forming a heterocyclic ring, R is an alkyl group of l to about 6 carbon atoms or a substituted alkyl group, a and n each is 1 or 2 and X is an anionic group used conventionally for cyanine dyes. (This compound is described in German Offenlegungsschrift No. 1,935,311.)

General Formula (II) wherein Z is an atomic group necessary for forming a cycloheptatriene ring, Z, is an oxygen atom, an Nl-l group or an -N= group, A is 0, a halogen atom or a pyrimidium group and B is a hydrogen atom, an alkoxycarbonyl group or an As such a xanthene type dye, a dye represented by I the following General Formula (Ill) is preferably used.

General Formula (lll) wherein X X X X and X each is a hydrogen atom or a halogen atom, q is l, 2, 3 or 4 and M is a hydrogen ion, an alkali metal ion or an ammonium ion. (This compound is described in German Offenlegungsschrift 1,935,331 1.)

The cyanine dye which is suitable is a dye, for example, represented by the following General Formula General Formula (IV) x :p ecu-cs 9 ii it in which and Z, are atomic groups for forming heterocyclic rings used conventionally as cyanine dye nuclei, such as B,B'-naphthoxazole, indolenine, benzothiazole, a-naphthothiazole and 4-quinoline nuclei, R and R,

each is an alkyl group, an allyl group or an aryl group,

L L and L;, are methine groups such as CH=,

X is an anionic group used conventionally for cyanine in which R,, R R and R each is a halogen atom, a hydroxyl group, an alkoxyl group, an aryloxy group, an arylthio group, an amino group, an alkylamino group and an arylamino group, Y and Y each are CH or a nitrogen atom and D is a divalent aromatic group such This compound is suitable for supersensitization of a sensitizing dye capable of spectrally sensitizing in the wavelength region of 600-720 nm of the M-band. Examples of compounds suitable for use in the invention are given in the following. These examples should not be interpreted as limiting the invention.

CH cs1 s 0 i c n C2H5 on cu CH CH3 No -CH=CH-CH= -A b s ca l uaco-cn -cawa-c a These color couplers are compounds capable of obtaining a color image using a color developing agent consisting of a p-phenylenediamine derivative such as, 1,2,4-triaminobenzen, l,2,4-triamino-5- methylbenzene, 2,3,6-triaminopyridine, 2- methylparaphenylenediamine, 2,5-dimethyl-pphenylenediamine, N-(p-dimethylaminophenylglycine, N,N-diethyl-pphenylenediamine and the like, see for example, U.S. Pat. No. 2,193,015 and the active methylene position of the color coupler may, during color developing, be substituted by a substituent which can be split imagewisely on development, for example, a substituent used in the conventional two equivalent type coupler, such as a halogen atom, a diazoaryl group, an arylthio group, an aryloxy groupor a carbonylgroup as disclosed in U.S. Pat. Nos. 3,311,476; 3,408,194; 3,419,391; and 3,417,928. Moreover, the production technique of the multi-layer direct positive type color photographic material consisting of at least two layers according to the invention is available for the color diffusion transfer system as well as the silver dye bleaching system which is well known in obtaining a color image.

Examples of the layer structure of a multi-layer photographic material of at least two layers will now be given in order to illustrate the invention in greater detail.

I. Direct positive type light-sensitive material whose exposure latitude is enlarged by the multilayer v 3 c c 11,

I ca structure without any lowering of the direct reversal sensitivity As illustrated hereinbefore, any of Emulsions A, B and C has the general characteristic of an emulsion which has a high sensitivity and improved clearance in that only a hard gradation is obtained. The commonly used method in the production of a light-sensitive material using the conventional negative type emulsion in order to enlarge the exposure latitude, for example, by mixing of different emulsions, by formation of a multilayer element or by addition of a dye results in not only a lowering of the reversal sensitivity and but also in a deterioration of the clearance, The present invention has a layer structure free from these disadvantages.

In FIG. 4, l is a support member, 2 and 3 are respectively direct positive-type emulsion layers and 4 is a protective layer which can be provided if desired.

FIG. 5 shows another embodiment wherein intermediate layer 5-is provided between emulsion layers 2 and 3 of FIG. 4. Provision of the intermediate layer can reduce any undesirable interaction occurring in the preparation of 2 and 3. In this intermediate layer superfine grain low sensitivity silver halide grains, silica grains, charged hydrophilic protective colloids, surface active agents and charged high molecular weight compounds such as sodium substituted naphthalenesulfonate are preferably added in order to prevent undesirable diffusion or transfer of the halogen acceptor or electron acceptor.

Table 3 shows examples of this layer structure.

sion 3) Table 3 Continued Emulsion 3 Emulsion 2 No. Emulsion Sensitiz- Emulsion Sensiti2- Developing 1 ype ing Sub- Type mg Sub- Method stance stance 2 B Electron acceptor A or C do. do. 3 A or C Halogen A or C Halogen Color acceptor acciptor development Electron Electron acceptor acceptor Color Color coupler coupler 4 B Electron B Electron do.

acceptor acceptor Color Color coupler coupler 5 B do. A or C Halogen do.

- acceptor Electron acceptor Color coupler. 6 A or C Halogen B Electron do.

acceptor acceptor Electron Color acceptor coupler Color coupler 'the recording of color images and drawings in the display system of cathode ray tube.

Referring to FIG. 6, l is an antihalation layer and 2 and 4 are direct positive type emulsion layers. 3 is an intermediate layer provided if desired and 5 is a protective layer provided if desired. Intermediate. layer 3 preferably has the functions of solving problems occurring due to undesirable diffusion and transfer of a halogen acceptor or electron acceptor, of acting as a filter layer, of protecting an emulsion layer thereon from irradiation and of improving the color separation due to the adjacent layer effect. For the filter layer or irradiation prevention layer, it is preferredto incorporate the conventionally used silver colloid and mordant consisting of the conventionally used acid dye as disclosed in US Pat; Nos. 3,282,699 and 3,512,983, and the positively charged hydrophilic polymer.

Table 4 shows examples of this layer structure.

Table 4 Emulsion Layer 4 Emulsion layer 2 No. Type Sensitizing Sub- Type Sensitizin Sub- Developstance and stance an Color Coupler Color Coupler ethod 7 B Electron accep- A or C Electron accep- Color tor (green tor (Halogen developsensmzatron) acceptor ment Supersensitizer Color coupler (red sensitim- (cyan) tion) +Color .coupler (red) 8 B do. B Electron accepdo.

tor (red sensitization) Color coupler (magenta) 9 A or C Electron accep- A or C Electron acceptdo.

tor Halogen tor (Halogen acceptor (ortho) acceptor +Color Supersensitizer coupler (magenta (red sensitive) -lColor coupler (cy n) 

1. A DIRECT POSITIVE-TYPE MULTI-LAYER LIGHT-SENSITIVE SILVER HALIDE MATERIAL HAVING HIGH INFORMATION PACKAGING CAPACITY COMPRISING A SUPPORT HAVING THEREON AT LEAST TWO EMULSION LAYERS SELECTED FROM THE GROUP CONSISTING OF (A) A CHEMICALLY FOGGED DIRECT POSITIVE-TYPE LIGHT-SENSITIVE SILVER HALIDE EMULSION IN WHICH AT LEAST ONE OF A HALOGEN ACCEPTOR AND AN ELECTRON ACCEPTOR IS ADSORBED ON THE SILVER HALIDE GRAINS, AND GRAINS HAVING FREE ELECTRON TRAPPING NUCLEI THEREIN, (B) A CHEMICALLY FOGGED DIRECT POSITIVE-TYPE LIGHT-SENSITIVE HALIDE EMULSION IN WHICH AT LEAST AN ELECTRON ACCEPTOR IS ADSORBED ON THE SILVER HALIDE GRAINS, SAID GRAINS BEING SUBSTANTIALLY FREE FROM POSITIVE HOLE TRAPPING NUCLEI THEREIN AND (C) A CHEMICALLY FOGGING DIRECT POSITIVE-TYPE LIGHT-SENSITIVE SILVER HALIDE EMULSION IN WHICH AT LEAST A HALOGEN ACCEPTOR IS ADSORBED ON THE SILVER HALIDE GRAINS, SAID GRAINS HAVING FREE ELECTRON TRAPPING NUCLEI THEREIN BUT BEING SUBSTANTIALLY FREE FROM POSITIVE HOLE TRAPPING NUCLEI THEREIN, SAID EMULSION EACH HAVING A DIFFERENT SENSITIZED WAVELENGTH REGION, SAID EMULSION LAYERS BEING THE SAME TYPE EMULSION LAYERS OR DIFFERENT TYPE EMULSION LAYERS HAVING THEREBETWEEN AN INTERMEDIATE LAYER PREVENTING DIFFUSION OR INTERACTION OF SAID ELECTRON ACCEPTOR OR HALOGEN ACCEPTOR BETWEEN SAID EMULSION LAYERS, THE HALOGEN ACCEPTOR OR ELECTRON ACCEPTOR IN AN EMULSION LAYER DIFFERING FROM THE HALOGEN ACCEPTOR OR ELECTRON ACCEPTOR IN AN EMULSION LAYER SENSITIZED TO A DIFFERENT WAVELENGTH REGION, SAID INTERMEDIATE LAYER ILLUSTRATING SUBSTANTIALLY NO DESENSITIZING EFFECT ON SAID EMULSION LAYERS.
 2. The direct positive-type multi-layer light-sensitive silver halide material of claim 1 wherein said material comprises at least two layers with an intermediate layer therebetween.
 3. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of the same type direct positive type light-sensitive silver halide emulsion selected from the group consisting of emulsion (A), emulsion (B) and emulsion (C).
 4. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers in which neither a layer of emulsion (A) nor emulsion (C) is present on a layer of emulsion (B).
 5. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of different types of direct positive-type light-sensitive silver halide emulsions, said different types being emulsion (A) and emulsion (B) or emulsion (B) and emulsion (C), said layers being obtained by simultaneous multi-layer coating.
 6. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers and where different type emulsion layers are present together an intermediate layer is contained therebetween.
 7. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least three emulsion layers with at leaSt one intermediate layer, said emulsion layers containing a blue-sensitive emulsion containing a yellow coupler, a green-sensitive emulsion containing a magenta coupler and a red-sensitive emulsion containing a cyan coupler.
 8. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two adjacent emulsion layers of the same emulsion type but different in direct reversal sensitivity.
 9. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two emulsion layers with an intermediate layer, said intermediate layer having incorporated therein a negative-type silver halide light-sensitive emulsion having a suitable spectral sensitivity and a corresponding amount of a color coupler whereby automatic masking of the unnecessary absorption of light by a direct positive image occurs.
 10. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor is a sensitizing dye of the M-band type in the 600 - 720 nm region.
 11. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor is a sensitizing dye having a cathodic polarographic half-wave potential more negative than -0.7 volts and wherein the difference between the cathodic polarographic half-wave potential and the anodic polarographic half-wave potential of said dye is greater than 1.5 volts.
 12. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said electron acceptor is a desensitizing dye compound having a cathodic polarographic half-wave potential more positive than 1.0 volt.
 13. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor and said electron acceptor are each present in said emulsion at a level ranging from about 1 X 10 6 to about 1 X 10 3 mole per mole of silver halide.
 14. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said intermediate layer comprises an emulsion layer having fine grain silver halide or silica therein.
 15. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer additionally contains a high molecular weight anionic organic compound or an anionic surface active agent.
 16. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer contains a color coupler whereby auto masking is provided.
 17. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said electron acceptor is a compound selected from the group of compounds having the general formulas
 18. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer comprises an emulsion layer having fine grain silver halide.
 19. The direct positive-type multi-layer light-sensitive silver halide material of claim 18, wherein said fine grain silver halide has a size less than about 0.2 microns.
 20. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said intermediate layer comprises an emulsion layer having silica therein.
 21. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said emulsion layers are different type emulsion layers.
 22. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (A) is capable of directly yielding a positive image without the electron acceptor or halogen acceptor.
 23. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (B) contains substantially no free electron trapping nuclei and is not capable of yielding a positive image without the electron acceptor, further wherein emulsion (B) is free from halogen acceptor.
 24. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (A) contains positive hole trapping nuclei.
 25. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of different types of direct positive-type light-sensitive silver halide emulsions, said different types being emulsion (A) and emulsion (C).
 26. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a desensitizing dye compound having a cathodic polarographic half-wave potential more positive than 1.0 volt.
 27. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (Ia).
 28. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (Ib).
 29. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (II).
 30. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (III).
 31. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (V).
 32. The direct positive-type multi-layer light-sensitive silver halide material of claim 31, wherein Z4 and Z1 are selected from the group consisting of a naphthoxazole, indolenine, benzothiazole, Alpha -naphthothiazole or quinoline nucleus. 